Coated platen design for plasma immersion ion implantation

ABSTRACT

A plasma treatment system ( 200 ) for implantation with a novel susceptor with a silicon coating ( 203 ). The system ( 200 ) has a variety of elements such as a chamber, which can have a silicon coating formed thereon, in which a plasma is generated in the chamber. The system ( 200 ) also has a susceptor disposed in the chamber to support a silicon substrate. The silicon coating reduces non-silicon impurities that may attach to the silicon substrate. In a specific embodiment, the chamber has a plurality of substantially planar rf transparent windows ( 26 ) on a surface of the chamber. The system ( 200 ) also has an rf generator ( 66 ) and at least two rf sources in other embodiments.

CROSS REFERENCES TO RELATED APPLICATIONS

The present patent application claims priority to U.S. ProvisionalPatent Application Ser. No. 60/074,397 filed Feb. 11, 1998, which ishereby incorporated by reference for all purposes.

The following two commonly-owned copending applications, including thisone, are being filed concurrently and the other one is herebyincorporated by reference in its entirety for all purposes:

1. U.S. patent application Ser. No. 09/215,094, allowed Chu et al.,entitled, “Coated Platen Design For Plasma Immersion Ion Implantation,”;and

2. U.S. patent application Ser. No. 09/216,035, now U.S. Pat. No.6,120,660 Chu et al., entitled, “Removable Liner Design For PlasmaImmersion Ion Implantation”.

BACKGROUND OF THE INVENTION

The present invention relates to the manufacture of integrated circuits.More particularly, the present invention provides a technique forselectively controlling a distribution of impurities that are implantedusing a plasma immersion ion implantation or plasma ion source systemfor the manufacture of semiconductor integrated circuits, for example.But it will be recognized that the invention has a wider range ofapplicability; it can also be applied to other substrates formulti-layered integrated circuit devices, three-dimensional packaging ofintegrated semiconductor devices, photonic devices, piezoelectronicdevices, microelectromechanical systems (“MEMS”), sensors, actuators,solar cells, flat panel displays (e.g., LCD, AMLCD), biological andbiomedical devices, and the like.

Integrated circuits are fabricated on chips of semiconductor material.These integrated circuits often contain thousands, or even millions, oftransistors and other devices. In particular, it is desirable to put asmany transistors as possible within a given area of semiconductorbecause more transistors typically provide greater functionality, and asmaller chip means more chips per wafer and lower costs. Some integratedcircuits are fabricated on a slice or wafer, of single-crystal(monocrystalline) silicon, commonly termed a “bulk” silicon wafer.Devices on such “bulk” silicon wafer typically use processing techniquessuch as ion implantation or the like to introduce impurities or ionsinto the substrate. These impurities or ions are introduced into thesubstrate to selectively change the electrical characteristics of thesubstrate, and therefore devices being formed on the substrate. Ionimplantation provides accurate placement of impurities or ions into thesubstrate. Ion implantation, however, is expensive and generally cannotbe used effectively for introducing impurities into a larger substratesuch as glass or a semiconductor substrate, which is used for themanufacture of flat panel displays or the like.

Accordingly, plasma treatment of large area substrates such as glass orsemiconductor substrates has been proposed or used in the fabrication offlat panel displays or 300 mm silicon wafers. Plasma treatment iscommonly called plasma immersion ion implantation (“PIII”) or plasmasource ion implantation (“PSI”). Plasma treatment generally uses achamber, which has an inductively coupled plasma source, for generatingand maintaining a plasma therein. A large voltage differential betweenthe plasma and the substrate to be implanted accelerates impurities orions from the plasma into the surface or depth of the substrate. Avariety of limitations exist with the convention plasma processingtechniques.

A major limitation with conventional plasma processing techniques is themaintenance of the uniformity of the plasma density and chemistry oversuch a large area is often difficult. As merely an example, inductivelyor transformer coupled plasma sources (“ICP” and “TCP,” respectively)are affected both by difficulties of maintaining plasma uniformity usinginductive coil antenna designs. Additionally, these sources are oftencostly and generally difficult to maintain, in part, because suchsources which require large and thick quartz windows for coupling theantenna radiation into the processing chamber. The thick quartz windowsoften cause an increase in rf power (or reduction in efficiency) due toheat dissipation within the window.

Other techniques such as Electron Cyclotron Resonance (“ECR”) andHelicon type sources are limited by the difficulty in scaling theresonant magnetic field to large areas when a single antenna orwaveguide is used. Furthermore, most ECR sources utilize microwave powerwhich is more expensive and difficult to tune electrically. Hot cathodeplasma sources have been used or proposed. The hot cathode plasmasources often produce contamination of the plasma environment due to theevaporation of cathode material. Alternatively, cold cathode sourceshave also be used or proposed. These cold cathode sources often producecontamination due to exposure of the cold cathode to the plasmagenerated.

A pioneering technique has been developed to improve or, perhaps, evenreplace these conventional sources for implantation of impurities. Thistechnique has been developed by Chung Chan of Waban Technology inMassachusetts, now Silicon Genesis Corporation, and has been describedin U.S. Pat. No. 5,653,811 (“Chan”), which is hereby incorporated byreference herein for all purposes. Chan generally describes techniquesfor treating a substrate with a plasma with an improved plasmaprocessing system. The improved plasma processing system, includes,among other elements, at least two rf sources, which are operative togenerate a plasma in a vacuum chamber. By way of the multiple sources,the improved plasma system provides a more uniform plasma distributionduring implantation, for example. It is still desirable, however, toprovide even a more uniform plasma for the manufacture of substrates.Additionally, Chan's techniques can create particulate contaminationduring implantation processes using his plasma processing system.

From the above, it is seen that an improved technique for introducingimpurities into a substrate is highly desired.

SUMMARY OF THE INVENTION

According to the present invention, a technique including a method andsystem for introducing impurities into a substrate using plasmaimmersion ion implantation is provided. In an exemplary embodiment, thepresent invention provides system with a novel susceptor with a coatingthat reduces particulate contamination that may attach to a substratesurface during an implantation process.

In a specific embodiment, the present invention provides a plasmatreatment system for implantation with a novel susceptor with a coatingthereon. The system has a variety of elements such as a chamber in whicha plasma is generated in the chamber. The system also has a susceptordisposed in the chamber to support a substrate such as a siliconsubstrate. A silicon bearing compound is coated on the susceptor forreducing impurities or non-silicon materials that may sputter off of thesusceptor. In a specific embodiment, the chamber has a plurality ofsubstantially planar rf transparent windows on a surface of the chamber.The system also has an rf generator and at least two rf sources in otherembodiments. A silicon bearing compound is coated onto the interiorsurfaces of the chamber. This coating reduces impurities or non-siliconmaterials that may sputter off of the interior surfaces of the chamberduring plasma immersion ion implantation.

In an alternative embodiment, the present invention provides a methodfor forming a substrate using a plasma immersion ion implantationsystem. The method includes a step of providing a silicon substrate,which has a surface, onto a susceptor within a plasma immersion ionimplantation chamber. The method then introduces and/or acceleratesparticles in a uniform, directional manner toward and into the surfaceto uniformly place the ions into a selected depth across a plane of thesubstrate. During the introducing step, the method sputters siliconbearing compounds off of interior chamber surfaces and portions of thesusceptor. These silicon bearing compounds do not detrimentallyinfluence the implantation process and reduce a possibility ofintroducing any impurities or non-silicon bearing compounds that canattach to the silicon substrate surface.

Numerous advantages are achieved by way of the present invention overconventional techniques. For example, the present invention provides arelatively easy to implement device for improving implantationuniformity across a substrate such as a wafer in a specific embodiment.In some embodiments, the present invention provides a system thatproduces fewer non-silicon particles (e.g., aluminum, iron, chrome,nickel) that may introduce defects into a substrate, for example. Instill other embodiments, the present invention can be implemented intoconventional PIII systems using kits or tools to provide the novelsilicon coatings. Accordingly, the present invention is generally costeffective and easy to implement. These and other advantages or benefitsare described throughout the present specification and are describedmore particularly below.

These and other embodiments of the present invention, as well as itsadvantages and features are described in more detail in conjunction withthe text below and attached Figs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified block diagram of a conventional plasma treatmentsystem; and

FIGS. 2-8 are simplified diagrams of plasma treatment systems accordingto embodiments of the present invention

DESCRIPTION OF SPECIFIC EMBODIMENTS

The present invention provides an improved plasma immersion ionimplantation system. In an exemplary embodiment, the present inventionprovides an improved pedestal (or susceptor) for securing a wafer duringimplantation. Additionally, the present invention provides a siliconcoating on interior surfaces of a chamber for reducing non-siliconimpurities that can attach to a silicon wafer surface. This improvedpedestal and silicon coating reduce provide fewer sputteredcontamination, which can be deposited on a surface of a substrate to beprocessed. By way of less contamination, the present system providesimproved substrates and the like.

1. Conventional Plasma Processing System

In brief overview and referring to FIG. 1, conventional plasmaprocessing system 10 includes a vacuum chamber 14 having a vacuum port18 connected to a vacuum pump (not shown). The system 10 includes aseries of dielectric windows 26 vacuum sealed by o-rings 30 and attachedby removable clamps 34 to the upper surface 22 of the vacuum chamber 14.Removably attached to some of these dielectric windows 26 are rf plasmasources 40, in a system having a helical or pancake antennae 46 locatedwithin an outer shield/ground 44. Cooling of each antenna isaccomplished by passing a cooling fluid through the antenna. Cooling istypically required only at higher power. The windows 26 without attachedrf plasma sources 40 are usable as viewing ports into the chamber 14.The removability of each plasma source 40 permits the associateddielectric window 26 to be cleaned or the plasma source 40 replacedwithout the vacuum within the system 10 being removed. Although glasswindows are used, other dielectric material such as quartz orpolyethylene may be used for the window material.

Each antenna 46 is connected to an rf generator 66 through a matchingnetwork 50, through a coupling capacitor 54. Each antenna 46 alsoincludes a tuning capacitor 58 connected in parallel with its respectiveantenna 46. Each of the tuning capacitors 58 is controlled by a signalD, D′, D″ from a controller 62. By individually adjusting the tuningcapacitors 85, the output power from each rf antenna 46 can be adjustedto maintain the uniformity of the plasma generated. Other tuning meanssuch as zero reflective power tuning may also be used to adjust thepower to the antennae. The rf generator 66 is controlled by a signal Efrom the controller 62. The controller 62 controls the power to theantennae 46 by a signal F to the matching network 50.

The controller 62 adjusts the tuning capacitors 58 and the rf generator66 in response to a signal A from a sensor 70 monitoring the powerdelivered to the antennae 46, a signal B from a fast scanning Langmuirprobe 74 directly measuring the plasma density and a signal C from aplurality of Faraday cups 78 attached to a substrate wafer holder 82.The Langmuir probe 74 is scanned by moving the probe (double arrow I)into and out of the plasma. With these sensors, the settings for the rfgenerator 66 and the tuning capacitors 58 may be determined by thecontroller prior to the actual use of the system 10 to plasma treat asubstrate. Once the settings are determined, the probes are removed andthe wafer to be treated is introduced. The probes are left in placeduring processing to permit real time control of the system. Care mustbe taken to not contaminate the plasma with particles evaporating fromthe probe and to not shadow the substrate being processed.

This conventional system has numerous limitations. For example, theconventional system 10 includes wafer holder 82 that is surrounded by aquartz liner 101. The quartz liner is intended to reduce unintentionalcontaminants sputtered from the sample stage to impinge or come incontact with the substrate 103, which should be kept substantially freefrom contaminates. Additionally, the quartz liner is intended to reducecurrent load on the high voltage modulator and power supply. The quartzliner, however, often attracts impurities or ions 104 that attachthemselves to the quartz liner by way of charging, as shown by FIG. 1A.By way of this attachment, the quartz liner becomes charged, whichchanges the path of ions 105 from a normal trajectory 107. The change inpath can cause non-uniformities during a plasma immersion implantationprocess. FIG. 1B shows a simplified top-view diagram of substrate 103that has high concentration regions 111 and 109, which indicatenon-uniformity. In some conventional systems, the liner can also be madeof a material such as aluminum. Aluminum is problematic in conventionalprocessing since aluminum particles can sputter off of the liner andattach themselves to the substrate. Aluminum particles on the substratecan cause a variety of functional and reliability problems in devicesthat are manufactured on the substrate. A wafer stage made of stainlesssteel can introduce particulate contamination such as iron, chromium,nickel, and others to the substrate. A paper authored by Zhineng Fan,Paul K. Chu, Chung Chan, and Nathan W. Cheung, entitled “Dose and EnergyNon-Uniformity Caused By Focusing Effects During Plasma Immersion IonImplantation,” published in Applied Physics Letters in 1998 describessome of the limitations mentioned herein.

In addition to the limitations noted above for the susceptor, numerouslimitations can also exist with the chamber. For example, commonly usedmaterials for the chamber include, among others, stainless steel oraluminum. These materials often sputter off the interior surfaces of thechamber and redeposit onto surfaces of a substrate, which is beingprocessed. The presence of these types of materials often placesnon-silicon bearing impurities onto the surface of a silicon wafer, forexample. These impurities can lead to functional, as well as reliabilityproblems, with integrated circuit devices that are fabricated on thesilicon substrate. Accordingly, conventional chambers also have severelimitations with conventional plasma immersion implantation systems.

2. Present Plasma Immersion Systems

FIG. 2 is a simplified overview of a plasma treatment system 200 forimplanting impurities according to an embodiment of the presentinvention. This diagram is merely and illustration and should not limitthe scope of the claims herein. One of ordinary skill in the art wouldrecognize other variations, modifications, and alternatives. For easyreading, some of the reference numerals used in FIG. 1 are used in FIG.2 and others. In a specific embodiment, system 200 includes a vacuumchamber 14 having a vacuum port 18 connected to a vacuum pump (notshown). The system 10 includes a series of dielectric windows 26 vacuumsealed by o-rings 30 and attached by removable clamps 34 to the uppersurface 22 of the vacuum chamber 14. Removably attached to some of thesedielectric windows 26 are rf plasma sources 40, in one embodiment havinga helical or pancake antennae 46 located within an outer shield/ground44. Other embodiments of the antennae using capacitive or inductivecoupling may be used. Cooling of each antenna is accomplished by passinga cooling fluid through the antenna. Cooling is typically required onlyat higher power. The windows 26 without attached rf plasma sources 40are usable as viewing ports into the chamber 14. The removability ofeach plasma source 40 permits the associated dielectric window 26 to becleaned or the plasma source 40 replaced without the vacuum within thesystem 10 being removed. Although glass windows are used in thisembodiment, other dielectric material such as quartz or polyethylene maybe used for the window material.

Each antenna 46 is connected to a rf generator 66 through a matchingnetwork 50, through a coupling capacitor 54. Each antenna 46 alsoincludes a tuning capacitor 58 connected in parallel with its respectiveantenna 46. Each of the tuning capacitors 58 is controlled by a signalD, D′, D″ from a controller 62. By individually adjusting the tuningcapacitors 85, the output power from each rf antenna 46 can be adjustedto maintain the uniformity of the plasma generated. Other tuning meanssuch as zero reflective power tuning may also be used to adjust thepower to the antennae. In one embodiment, the rf generator 66 iscontrolled by a signal E from the controller 62. In one embodiment, thecontroller 62 controls the power to the antennae 46 by a signal F to thematching network 50.

The controller 62 adjusts the tuning capacitors 58 and the rf generator66 in response to a signal A from a sensor 70 (such as a Real PowerMonitor by Comdel, Inc., Beverly, Mass.) monitoring the power deliveredto the antennae 46, a signal B from a fast scanning Langmuir probe 74directly measuring the plasma density and a signal C from a plurality ofFaraday cups 78 attached to a substrate wafer holder 82. The Langmuirprobe 74 is scanned by moving the probe (double arrow I) into and out ofthe plasma. With these sensors, the settings for the rf generator 66 andthe tuning capacitors 58 may be determined by the controller prior tothe actual use of the system 10 to plasma treat a substrate. Once thesettings are determined, the probes are removed and the wafer to betreated is introduced. In another embodiment of the system, the probesare left in place during processing to permit real time control of thesystem. In such an embodiment using a Langmuir probe, care must be takento not contaminate the plasma with particles evaporating from the probeand to not shadow the substrate being processed. In yet anotherembodiment of the system, the characteristics of the system aredetermined at manufacture and the system does not include plasma probe.

In a specific embodiment, the present system includes a novel susceptordesign 82 using a silicon coating 205. The silicon coating 205 isdefined on substantially all surfaces, including top, sides, and bottom,of the susceptor 82, which holds silicon wafer 201. The silicon coatingincludes a silicon bearing compound. In most embodiments, the siliconcoating is desirable in a process using silicon wafers or the like. Thecoating can be made of any suitable material that is sufficientlyresistant to implantation and temperature influences. As merely anexample, the silicon coating can be an amorphous silicon layer, acrystalline silicon, or a polysilicon thickness for providing protectionor isolating the base susceptor material 211, as shown in FIG. 2A, forexample. The silicon coating can be applied to the susceptor using avariety of deposition techniques such as chemical vapor deposition,physical vapor deposition, and others. The base susceptor material canbe a variety of materials such as stainless steel, aluminum, and others.Accordingly, an ion 213 impinging on susceptor coating 205 can remove asilicon bearing compound that is deposited on substrate 201. Since thecoating is made of the same or similar material as the silicon substrate201, substantially no damage occurs to the substrate during implantationof ions 207. The silicon coating is often about 0.5 micrometers to about2.0 micrometers or thicker, depending upon the embodiment.

In another embodiment, the present invention also includes a siliconcoating 203 that is defined on the interior surfaces of the chamber. Thesilicon coating includes a silicon bearing compound. In mostembodiments, the silicon coating is desirable in a process using siliconwafers or the like. The coating can be made of any suitable materialthat is sufficiently resistant to implantation and temperatureinfluences. The silicon coating can be applied to the susceptor using avariety of deposition techniques such as chemical vapor deposition,physical vapor deposition, and others. As merely an example, the siliconcoating can be an amorphous silicon layer, a crystalline silicon, or apolysilicon thickness for providing protection or isolating the basechamber material 215. The silicon coating is often about 0.5 micrometersto about 2.0 micrometers or thicker, depending upon the embodiment. Thebase chamber material can be a variety of materials such as stainlesssteel, aluminum, and others. Accordingly, an ion 209 impinging onsilicon coating 203 can remove a silicon bearing compound from thecoating that is deposited on substrate 201. Since the coating is made ofthe same or similar material as the silicon substrate 201, substantiallyno damage occurs to the substrate during implantation of ions 207.

In an alternative embodiment, the interior chamber coating can be formedusing a silicon liner material. FIG. 2B is a simplified top-view diagramof system 200 having a silicon liner according to the present invention.The system shows a variety of elements such as base chamber material 215and silicon coating 203 or liner that is defined on the base chambermaterial. Additionally, the system includes a feed location 221 and anexhaust location 223. In this specific embodiment, the system includeschamber walls that are made of panels 225, which are circularly shaped(i.e., polygon) to form a cylindrically shaped liner. The panels areattached to each other using fasteners or welded together. Each panel ismade of a plurality of flat silicon substrates 227, which are eachhoused in a frame 229. The silicon substrates can be in the form ofsquare wafers and the frame can be made of stainless steel or the like.

FIGS. 2C and 2D are simplified side-view diagrams of an expanded chambersidewall or liner according to embodiments of the present invention. Theexpanded chamber sidewall illustrates a plurality of silicon substrates227, which are grouped together to form panels 253. The panels runparallel to each other and are folded in a manner to form thecylindrically shaped liner. Each of the substrates is housed or disposedin stainless steel frame 229 and aligned vertically to form the panel.The frame runs in horizontal and vertical sections, which are normal toeach other for strength and design. The chamber sidewall also includesopenings 228 and 231 for facilities or chamber elements, e.g., sensors.Each substrate is housed in frame 229, which is covered by thesubstrate. That is, the frame is not exposed to the interior of thechamber. A stainless steel clip 233 holds or secures each of substrateinto the frame. The clip generally uses friction forces to secure theclip into the frame, which holds the substrate. In this embodiment, aportion of the stainless steel clip is exposed to the interior of thechamber.

FIG. 2E is an expanded top-view diagram of a chamber, having the siliconcoating and liner, according to embodiments of the present invention.The chamber includes a variety of elements such as panel 253, which ismade of the plurality of silicon substrates 227. The susceptor is coated205 also with silicon. A bottom region 251 of the chamber, whichunderlies the susceptor, is also lined with silicon. As shown, thepanels are attached to each other to form a cylindrical liner. Thecylindrical liner lines the interior periphery of the chamber to provide“walls” for the chamber. A bottom portion of the housing sits on thebottom region 251. A top portion of the housing faces a chamber top thatholds the inductive coils. Most of the interior surfaces of the chamberare lined with silicon material, including the silicon coating, siliconliner, and others. In a specific embodiment, the interior surfaces areat least 70% silicon or at least 90% silicon, but are not limited tothese percentages.

FIG. 2F is a simplified perspective diagram 200 of chamber liner, whichis not in the chamber. The liner is often assembled outside of thechamber for manufacturing ease. The liner is then placed into thechamber. In particular, a chamber top is removed to expose the innerportion of the chamber. The chamber liner is lifted from an outsideposition, and is inserted into the chamber opening. Depending upon theapplication, the chamber liner can be fastened to the bottom of thechamber, as well as the top of the chamber by way of screws, snaps, andother fasteners. In one embodiment, the chamber liner can be removedfrom the chamber by removing the fasteners and lifting the liner outfrom the top portion of the chamber. A substrate in the liner can oftenbecome damaged or the like. Rather than replacing one of the siliconsubstrates in the chamber, the entire liner can be removed andreconditioned.

Although the above description have been generally described in terms ofa silicon liner, it can be replaced by a variety of other materials. Forexample, the silicon liner can be replaced by quartz or other impurityfree material. Depending upon the application, one of ordinary skill inthe art would recognize other variations, modifications, andalternatives.

Referring to FIG. 3, the configuration of plasma sources 40 may be suchthat a plurality of physically smaller plasma sources 40 produce auniform plasma over an area greater than that of sum of the areas of theindividual sources. In the embodiment of the configuration shown,four-inch diameter plasma sources 40 spaced at the corners of a squareat six inch centers produce a plasma substantially equivalent to thatgenerated by a single twelve inch diameter source. Therefore, byproviding a vacuum chamber 14 with a plurality of windows 26, thevarious configurations of plasma sources 40 may be formed to produce auniform plasma of the shape and uniformity desired. Antennae such asthose depicted do not result in rf interference between sources whenproperly shielded as shown.

Multiple rf plasma sources can excite electron cyclotron resonance inthe presence of a multi-dipole surface magnetic field. Such a surfacemagnetic field would, for example, be approximately 1 KG at the poleface and would drop to a few Gauss at about 10 cm. from the pole face.In such a system, electron cyclotron resonance may be established, withthe electron cyclotron resonance frequency (in Hz) being given by theexpression nu=2.8×10⁶ (B) where B is the magnetic field strength inGauss. Thus, if the fundamental electron cyclotron resonance frequencyis 13.56 MHz (that is, the frequency supplied by the rf generator) themagnetic field required (as applied by the magnets) is 4.8 G, forresonance coupling to take place. Higher harmonics of the fundamentalresonance frequency may be achieved by increasing the magnetic fieldproportionately. Thus for a second harmonic to be coupled, the magneticfield would have to be increased to 9.6 G. Such ECR coupling is mosteffective at lower pressures (P<1 mTorr). The use of the small rf plasmasources permit such magnets to be positioned so as to make electroncyclotron resonance possible.

The Faraday cups 78 used to measure the uniformity of the field and theplasma dose, in one embodiment, are positioned near one edge in thesurface of the wafer holder 82 (FIG. 4). The flat edge 86 of wafer 90 ispositioned on the wafer holder 82 such that Faraday cups 78 of the waferholder 82 are exposed to the plasma. In this way the plasma doseexperienced by the wafer 90 can be directly measured. Alternatively, aspecial wafer 90′, as shown in FIG. 4A, is fabricated with a pluralityof Faraday cups 78 embedded in the wafer 90′. This special wafer 90′ isused to set the rf generator 66 and the tuning capacitors 58 to achievethe desired plasma density and uniformity. Once the operating parametershave been determined, the special wafer 90′ is removed and the wafers 90to be processed placed on the wafer holder 82.

Referring to FIG. 5, although the system 200 has been described in termsof a planar array of plasma sources 40 located on the upper surface ofthe vacuum chamber 14, the plasma sources 40 may be distributed overother surfaces of the vacuum chamber 14′ to generate a uniform volume ofplasma. Such a system is particularly effective in batch processing.

Referring to FIG. 6, in another embodiment, a quartz window 100 is notattached to the vacuum chamber 14, but instead encloses one end of theshield 44 of the plasma source 40′. In this embodiment, a tube 104attached to an opening 108 in the quartz window 100 provides a gas feedto form a plasma of a specific gas. In this case, the plasma source 40′is not attached to a window 26 in the wall of the vacuum chamber 14, butis instead attached to the vacuum chamber 14 itself. Such plasma sources40′ can produce plasmas from specific gasses as are required by manyprocesses. Several such plasma sources 40′ can be aligned tosequentially treat a wafer 90 with different plasmas as in theembodiment of the in line system shown in FIG. 7. In this embodiment,wafers 90 are moved by a conveyor 112 through sequential zones, in thisembodiment zones I and II, of a continuous processing line 114. Eachzone is separated from the adjacent zones by a baffle 116. In oneembodiment, the gas in zone I is SiH₄ used in Si-CVD processing, whilethe gas in zone II is PH₃ used in doping. In another embodiment, acluster tool having load-locks to isolate each processing chamber fromthe other chambers, and equipped with a robot includes the rf plasmasources 40 of the invention for plasma CVD and plasma etching.

FIG. 8 depicts an embodiment of the system of the invention using twoplasma sources. In this embodiment each source is an inductive pancakeantenna 3-4 inches in diameter. Each antenna 46 is constructed of a ¼inch copper tube and contains 5-6 turns. Each antenna 46 is connected toa matching network 50 through a respective 160 pf capacitor. Thematching network 50 includes a 0.03 mu H inductor 125 and two variablecapacitors 130, 135. One variable capacitor 130 is adjustable over therange of 10-250 pf and the second capacitor 135 is adjustable over therange of 5-120 pf. The matching network 50 is tuned by adjusting thevariable capacitor 130, 135. The matching network 50 is in turnconnected to an rf source 66 operating at 13.56 mHz. A series of magnets140, 145 are positioned around the circumference of the chamber inalternating polarity every 7 cm to form a magnetic bucket.

With the chamber operating at 1 m Torr pressure, the power to theantenna 46 is 25 W per antenna or about 50 W total. With the pressure inthe chamber reduced to 0.1 m Torr, the power is increased to 200 W perantenna or 400 W total. The resulting plasma at 50 W total power has asubstantially uniform density of 10¹¹ atoms/cm³. The uniformity and thedensity may be further improved using four of such sources. With thechamber operating at 1 m Torr pressure, the power to the antenna 46 is25 W per antenna or about 50 W total. With the pressure in the chamberreduced to 0.1 m Torr, the power is increased to 200 W per antenna or400 W total. The resulting plasma at 50 W total power has asubstantially uniform density of 10¹¹ atoms/cm³. The uniformity and thedensity may be further improved using four of such sources.

In a specific embodiment, the present invention operates at hightemperature for light particle implanting processes. The light particleprocess can implant a variety of materials such as hydrogen, helium,quartz, and others. The light particles, which are implanted at hightemperature, do not accumulate in any of the chamber materials, e.g.,silicon, silicon liner. They tend to diffuse out of such materials,which prevents “pealing” of the silicon or silicon liner material. Inmost embodiments, implanting of a hydrogen bearing compound (e.g., H₂)occurs at about 400 and greater to about 500 Degrees Celsius. The hightemperature operation generally does not allow any of the lightparticles to cause damage to the silicon or silicon liner material.

While the above description is generally described in a variety ofspecific embodiments, it will be recognized that the invention can beapplied in numerous other ways. For example, the improved susceptordesign can be combined with the embodiments of the other Figs.Additionally, the embodiments of the other Figs. can be combined withone or more of the other embodiments. The various embodiments can befurther combined or even separated depending upon the application.Accordingly, the present invention has a much wider range ofapplicability than the specific embodiments described herein.

Although the above has been generally described in terms of a PIIIsystem, the present invention can also be applied to a variety of otherplasma systems. For example, the present invention can be applied to aplasma source ion implantation system. Alternatively, the presentinvention can be applied to almost any plasma system where ionbombardment of an exposed region of a pedestal occurs. Accordingly, theabove description is merely an example and should not limit the scope ofthe claims herein. One of ordinary skill in the art would recognizeother variations, alternatives, and modifications.

While the above is a full description of the specific embodiments,various modifications, alternative constructions and equivalents may beused. Therefore, the above description and illustrations should not betaken as limiting the scope of the present invention which is defined bythe appended claims.

What is claimed is:
 1. A plasma immersion ion implantation (PIII)treatment system for implantation, said system comprising: a chamber inwhich a plasma is generated in said chamber, said chamber having abottom region exposed to the plasma and lined with silicon; and asilicon coated susceptor disposed in said chamber to support a siliconsubstrate, said silicon coated susceptor providing fewer non-siliconbearing impurities that can be sputtered off of the susceptor during animplantation process.
 2. The system of claim 1 wherein said chambercomprises a plurality of substantially planar rf transparent windows ona surface of said chamber.
 3. The system of claim 1 further comprising:an rf generator; and at least two rf sources, each external to saidvacuum chamber and each said rf source electrically connected to said rfgenerator and juxtaposed to a respective one of said plurality rftransparent windows, and operative to generate said plasma in the vacuumchamber; said rf sources operative to produce a local, substantiallyuniform plasma proximate said substrate.
 4. The system of claim 3further comprising at least one tuning circuit, each said at least onetuning circuit electrically connected to one of said at least two rfsources.
 5. The system of claim 1 wherein said silicon coated susceptorhas a coating selected from polysilicon, amorphous silicon, orcrystalline silicon.
 6. The system of claim 5 wherein said siliconcoated susceptor has a base metal selected from stainless steel oraluminum.
 7. The system of claim 1 wherein said silicon substrate is asilicon bearing wafer.
 8. The system of claim 1 wherein said chambercomprises a silicon coating defined on an interior region of saidchamber, said silicon coating providing fewer non-silicon impuritiesonto said silicon substrate, said non-silicon impurities can besputtered off of said chamber.
 9. The system of claim 8 wherein saidsilicon coating is selected from amorphous silicon, polysilicon, orcrystalline silicon.
 10. The system of claim 8 wherein said chambercomprises an aluminum bearing material underlying said silicon coating.11. The system of claim 1 wherein said system is provided in a clustertool.
 12. A method for forming a substrate, said method comprising stepsof: providing a substrate onto a silicon coated susceptor within aplasma immersion ion implantation chamber, said substrate comprising asilicon wafer with a surface, and said chamber having a bottom surfaceexposed to a plasma and lined with silicon; introducing particles in adirectional manner toward and through said surface of said substrate touniformly place said ions into a selected depth across a plane of saidsubstrate; and sputtering silicon bearing material off of said siliconcoated susceptor, said silicon bearing material being attached to saidsurface of said substrate.
 13. The method of claim 12 wherein saidsilicon coated susceptor comprises a material selected from an amorphoussilicon, polysilicon, or crystalline silicon.
 14. The method of claim 12wherein said silicon coated susceptor comprises a base material selectedfrom aluminum or stainless steel.
 15. The method of claim 12 whereinsaid substrate comprises silicon wafer.
 16. The method of claim 12wherein said chamber comprises a silicon coating defined on interiorsurfaces of said chamber.
 17. The method of claim 16 wherein saidsilicon coating is selected from amorphous silicon, polysilicon, orcrystalline silicon.
 18. The method of claim 12 wherein said methodoccurs in a cluster tool.